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71.
In this paper we consider the problem of identifying the most influential (or central) group of nodes (of some predefined size) in a network. Such a group has the largest value of betweenness centrality or one of its variants, for example, the length-scaled or the bounded-distance betweenness centralities. We demonstrate that this problem can be modelled as a mixed integer program (MIP) that can be solved for reasonably sized network instances using off-the-shelf MIP solvers. We also discuss interesting relations between the group betweenness and the bounded-distance betweenness centrality concepts. In particular, we exploit these relations in an algorithmic scheme to identify approximate solutions for the original problem of identifying the most central group of nodes. Furthermore, we generalize our approach for identification of not only the most central groups of nodes, but also central groups of graph elements that consists of either nodes or edges exclusively, or their combination according to some pre-specified criteria. If necessary, additional cohesiveness properties can also be enforced, for example, the targeted group should form a clique or a κ-club. Finally, we conduct extensive computational experiments with different types of real-life and synthetic network instances to show the effectiveness and flexibility of the proposed framework. Even more importantly, our experiments reveal some interesting insights into the properties of influential groups of graph elements modelled using the maximum betweenness centrality concept or one of its variations. 相似文献
72.
We present CGO-AS, a generalized ant system (AS) implemented in the framework of cooperative group optimization (CGO), to show the leveraged optimization with a mixed individual and social learning. Ant colony is a simple yet efficient natural system for understanding the effects of primary intelligence on optimization. However, existing AS algorithms are mostly focusing on their capability of using social heuristic cues while ignoring their individual learning. CGO can integrate the advantages of a cooperative group and a low-level algorithm portfolio design, and the agents of CGO can explore both individual and social search. In CGO-AS, each ant (agent) is added with an individual memory, and is implemented with a novel search strategy to use individual and social cues in a controlled proportion. The presented CGO-AS is therefore especially useful in exposing the power of the mixed individual and social learning for improving optimization. The optimization performance is tested with instances of the traveling salesman problem (TSP). The results prove that a cooperative ant group using both individual and social learning obtains a better performance than the systems solely using either individual or social learning. The best performance is achieved under the condition when agents use individual memory as their primary information source, and simultaneously use social memory as their searching guidance. In comparison with existing AS systems, CGO-AS retains a faster learning speed toward those higher-quality solutions, especially in the later learning cycles. The leverage in optimization by CGO-AS is highly possible due to its inherent feature of adaptively maintaining the population diversity in the individual memory of agents, and of accelerating the learning process with accumulated knowledge in the social memory. 相似文献
73.
针对地方高校本科计算机专业数据库课程教学进行研究,首先详细分析了地方高校应用型本科该专业课程的培养目标;其次通过设置数据库课程群和课程链,制定了数据库相关系列课程的体系结构;最后对地方高校应用型本科计算机专业数据库系列课程的教学方法和考核方式进行了探讨. 相似文献
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76.
LiuZhong ZhouYunfei LiPeigen Duan Zhengcheng School of Mechanical Science Engineering Huazhong University of Science Technology Wuhan China Manufacturing Production 《计算机辅助绘图.设计与制造(英文版)》2001,(2)
We propose in this paper a genetic algorithm (GA)-based approach to solve the Flexible Manufacturing System (FMS) formation problem. First, we divide the unity of machines into small groups or cells using Group Technology (GT). And an option for considering the minimization of workload variation between cells is included. Then the implementation is done using GA. When using GA, the designer is allowed to specify the number of cells and impose lower and upper bounds on cell size. This makes the GA scheme flexible for solving the FMS formation problems. 相似文献
77.
Barry Brian Werger Maja J. Matarić 《Annals of Mathematics and Artificial Intelligence》2001,31(1-4):173-197
Ant-like systems take advantage of agents' situatedness to reduce or eliminate the need for centralized control or global knowledge. This reduces the need for complexity of individuals
and leads to robust, scalable systems. Such insect-inspired situated approaches have proven effective both for task performance
and task allocation. The desire for general, principled techniques for situated interaction has led us to study the exploitation
of abstract situatedness – situatedness in non-physical environments. The port-arbitrated behavior-based control approach provides a well-structured abstract behavior space in which agents can participate in situated interaction. We focus on the problem of role assumption, distributed task allocation in which each agent selects its own task-performing role. This paper details our general, principled
Broadcast of Local Eligibility (BLE) technique for role-assumption in such behavior-space-situated systems, and provides experimental
results from the CMOMMT target-tracking task.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
78.
Mireille Boutin 《International Journal of Computer Vision》2000,40(3):235-248
Corrected versions of the numerically invariant expressions for the affine and Euclidean signature of a planar curve introduced by Calabi et al. in (Int. J. Comput. Vision, 26: 107–135, 1998) are presented. The new formulas are valid for fine but otherwise arbitrary partitions of the curve. We also give numerically invariant expressions for the four differential invariants parameterizing the three dimensional version of the Euclidean signature curve, namely the curvature, the torsion and their derivatives with respect to arc length. 相似文献
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